Radio stopped working

The radio turns on and 'appears' to function but no sound. When it is first turned on , there is a pop from the rear driver speaker. Does anyone know if there is an external amp or if it is all included in the radio?
 
Thanks
 

I have a 2005 and the radio would go fuzzy after an hour or so of use. A real pain on a road trip. The cd would do the same. The radio's / cd players are amped internally. I made an appointment to have it fixed and cancelled it and bought a clarion 200 watt radio/cd /sat ready unit for 149.00. All the power you need and the original speakers will hold it.

yeah its normal time to go with an aftermarket stereo :(